Below, a summary of the related art and background art relating to the present invention will be explained.
An example of the communication method will be explained illustrating the Internet as an example of a network (communication network).
WWW Service
The WWW (World Wide Web), as is well known, is one of the information services of the Internet. Namely, the WWW service is established by transmitting information written by a language such as HTML (HyperText Markup Language) using a client/server type protocol (communication agreement) referred to as HTTP (HyperText Transfer Protocol) between a client usually using a personal computer (PC), that is, a Web browser, and a server.
The Web browser carried in the client PC has as its main role to access a URL (Uniform Resource Locator) designated by a user and display the information. As Web browsers, Microsoft's Internet Explorer and Netscape Communications' Netscape Navigator are famous.
When obtaining information from a server using a Web browser, text files having file extensions such as “.html” or “.htm” are sent from the server to the Web browser. These files are written in the HTML language and are document files of a type referred to as HyperText documents.
“HyperText” means a mechanism burying link information to another document in a certain character string in a document freely prepared by the user and enabling other information to be referred to by selecting that character string.
In WWW, by utilizing this HyperText mechanism, the information can be freely comprised by freely extending the link from a local resource of the server to a resource on the network.
Extensions are continuously being added to the specifications of HTML at present. Image, audio, and other data are also now being handled.
CGI, ISAPI
CGI (Common Gateway Interface) means the specification (interface) for extending a function by an API (Application Programming Interface) connecting a Web server and another program operating on the server.
An application using CGI is prepared by a C language, Perl language (type of script language), etc. and operates to return some sort of answer with respect to a value transferred from the browser in cooperation with an application operating on the server.
On the other hand, ISAPI (Internet Server Application Programming Interface) operates to return some sort of answer with respect to information transferred from the browser in the same way as a DLL (Dynamic Link Library). ISAPI takes the form of a DLL operating in a process space of a server.
Both CGI and ISAPI are applications appearing to operate on a server. By using CGI and ISAPI, a Web server having only the function of displaying HTML pages prepared in advance can be given more diverse functions.
Communication Between Web Browser and Web Server
FIG. 1 is a view illustrating the flow of processing when accessing a Web page placed inside a server and programmed by only HTML from a browser of a client personal computer (PC).
In FIG. 1, when the browser sends a request to the Web server, the Web server reads the requested file and sends back a response to the browser of the client PC. In this case, it is also possible for the browser to inquire about an IP address of a target Web server corresponding to the URL designated with respect to the DNS server via the Internet and send the request to the Web server by using the found IP address.
FIG. 2 is a view illustrating the flow of the processing in the case of accessing a Web page containing a CGI or ISAPI application.
When information from the client PC is necessary, it is also possible to explicitly send the information to the server from an area described by a tag referred to as a “form” programmed by HTML. The Web server starts up the application of ISAPI or CGI and performs the processing by the server application according to the data transferred from the client browser (client PC).
The Web server sends back the processed result again to the client browser as a response.
Recent Use of Method of Using Browser
Recently, a Web server does not only extract information existing in the server. It is also possible to send information of a client PC to the Web server, process that information by ISAPI or CGI, and return it to the client PC. Due to this, the relationship between browsers and Web servers, which has been utilized as an information network called the Internet hitherto, is now being applied to other areas too.
As an example of this, there may be mentioned a remote control system and method for remote control of an apparatus such as a household electrical appliance.
A Web server function explained by illustration in FIG. 1 and FIG. 2 is incorporated in an apparatus to be remote controlled and connected to a network, for example, the Internet.
As opposed to this, the browser on the client side corresponding to a remote controller such as a TV receiver remote controller and air conditioner remote controller sends a command corresponding to a command of the remote controller to the apparatus (Web server) via the network.
Then, according to the content of the arrived command, the Web server can perform an operation just like if it were operated by a remote controller in place of a command which can be understood for the inside of the apparatus by a server application (ISAPI, CGI).
FIG. 3 is a view of an outline of a remote control system in the case of using a projector as an apparatus controlled by a remote controller explained above.
FIG. 3 illustrates a configuration for remote control of a projector 1 using a remote controller RC having a browser function. The projector 1 has the function of a Web browser. In FIG. 3, the Internet is not used as the network. A infrared ray is propagated through the space between the remote controller RC and projector 1.
Recent projectors have personal computers built in the projectors per se and have liquid crystal display devices, polarizing means, etc. built in. They can directly receive video information from the personal computers, process that information, project images in colors. Therefore, it is easy to install servers in personal computers mounted in such projectors.
When controlling the projector proper by the remote controller RC in such a remote controlled system, the remote controller RC is operated within a range where infrared rays of the remote controller RC can reach and facing the projector proper. Then, the projector having the function of a server performs processing for control according to the instructions of the remote controller. The projector performs processing in accordance with the results.
FIG. 4 is a view of the configuration wherein a projector 12 and a client PC (browser) 11 are connected via a network 15.
The client PC 11 carries the browser function, while the projector 12 carries the Web server function.
The projector 12 also has built into it, other than the personal computer having the function of a Web server, a liquid crystal display, polarizing means, etc. It is configured to be able to project images in color by using the personal computer of the server or using a built-in second personal computer for video display or image processing apparatus to directly receive and process video information from a personal computer outside of the projector 12.
FIG. 5 is a flow chart of the processing of a server in the projector 12 in FIG. 4.
Step 1, 2: A screen of a remote controller RC showing a list of commands is first formed on the Web in advance. The URL of that screen is designated from the browser (client PC) 11 by using a network line 15.
Step 3: The server carried in the projector 12 returns the screen information showing the list of commands to the browser (client PC) 11. Thereafter, by selecting a command corresponding to the desired remote control operation from the list at the browser 11, the command information is transferred to the server.
Step 4: The server in the projector 12 controls the apparatus in place of commands inside the apparatus by the server application (CGI, ADAPI) based on that information.
Step 5: The server in the projector 12 sends back a response of the end of operation to the browser (client PC) 11 which sent the request.
Step 6: The client browser 11 receives that response and replies in accordance with that content. The method of reply is to make another request, terminate the operation, etc.
Step 7: So long as there is a request from the client browser 11, the above processing is repeated.
However, the following problem is encountered when a client browser is used as a controller in the configuration and method explained above. Namely, when controlling an apparatus by using the browser of the client, the server installed in the apparatus to be controlled, and the application thereof, the problem arises that the screen is instantaneously switched for redrawing when the same operation is repeated or the like and the screen becomes hard to view. Details will be explained below.
In general, when employing a usage method like a remote control operation, a usage method continuing the same command is frequently used.
If it is desired to realize this by the method of issuing a request to the server installed in the apparatus under the control of the browser, in the HTTP protocol, one response is always returned for one command (request). The browser to which the response is returned re-draws the browser screen in accordance with the content of the response. This being so, when the same command is continuously sent, the screen will be continuously re-drawn. At this time, a phenomenon of the screen switching many times in a short time arises, so a situation like a blinking (flashing) screen is exhibited. Such a phenomenon becomes a visually obstacle and results in poor response of the control operation and poor operability overall.
In the above example, the explanation was given taking as an example a projector as the apparatus, but a problem similar to the above is encountered in the case of remote control of various other types of apparatuses as well. That is, the apparatus to be controlled is not limited to a projector. All apparatuses connected to for example a network can be covered as the network. That is, a similar problem to the above is also encountered in the case where a home server or the like is installed in the apparatus.